scsh-0.6/scheme/vm/stob.scm

99 lines
2.9 KiB
Scheme

; Copyright (c) 1993-1999 by Richard Kelsey and Jonathan Rees. See file COPYING.
(define max-stob-size-in-cells
(+ max-stob-contents-size-in-cells
stob-overhead))
(define (make-stob type len key)
(let ((addr (s48-allocate-space type (+ len (cells->bytes stob-overhead)) key)))
(store! addr (make-header type len))
(address->stob-descriptor (address+ addr (cells->bytes stob-overhead)))))
(define (make-d-vector type len key)
(make-stob type (cells->bytes len) key))
(define make-b-vector make-stob)
; Used to copy stuff from the stack to the heap.
(define (header+contents->stob header contents key)
(let* ((addr (s48-allocate-space (header-type header)
(+ (header-length-in-bytes header)
(cells->bytes stob-overhead))
key))
(data-addr (address+ addr (cells->bytes stob-overhead))))
(store! addr header)
(copy-memory! contents data-addr (header-length-in-bytes header))
(address->stob-descriptor data-addr)))
(define (stob-type obj)
(header-type (stob-header obj)))
(define (stob-of-type? obj type)
(and (stob? obj)
(= (stob-type obj) type)))
; Immutability
(define (immutable? thing)
(or (not (stob? thing))
(immutable-header? (stob-header thing))))
(define (make-immutable! thing)
(if (not (immutable? thing))
(stob-header-set! thing (make-header-immutable (stob-header thing)))))
; D-vectors (vectors of descriptors)
(define (d-vector? obj)
(and (stob? obj)
(< (header-type (stob-header obj)) least-b-vector-type)))
; The type in these routines is used only for internal error checking.
(define (d-vector-length x)
(assert (d-vector? x))
(header-length-in-cells (stob-header x)))
(define (d-vector-ref x index)
(assert (valid-index? index (d-vector-length x)))
(fetch (address+ (address-after-header x) (cells->a-units index))))
(define (d-vector-set! x index value)
(assert (valid-index? index (d-vector-length x)))
(let ((addr (address+ (address-after-header x) (cells->a-units index))))
(s48-write-barrier x addr value)
(store! addr value)))
(define (d-vector-init! x index value)
(assert (valid-index? index (d-vector-length x)))
(store! (address+ (address-after-header x) (cells->a-units index))
value))
; B-vector = vector of bytes.
(define (b-vector? obj)
(and (stob? obj)
(>= (header-type (stob-header obj))
least-b-vector-type)))
(define (b-vector-length x)
(assert (b-vector? x))
(header-length-in-bytes (stob-header x)))
(define (b-vector-ref b-vector index)
(assert (valid-index? index (b-vector-length b-vector)))
(fetch-byte (address+ (address-after-header b-vector) index)))
(define (b-vector-set! b-vector index value)
(assert (valid-index? index (b-vector-length b-vector)))
(store-byte! (address+ (address-after-header b-vector) index) value))
; Various utilities
(define (valid-index? index len)
(and (>= index 0) (< index len)))